Seriously, I gotta ask

Being an ALT (Assistant Language Teacher) in Japan can be really interesting sometimes.
One of the more interesting aspects of my job is to follow along what the Japanese teachers are required to use to teach English in schools.
Their textbook which is called Sunshine has songs for cloze exercises, or to give their students a chance to hear English being used for real.
However, what I take issue with is the use of Carpenters songs. Now, don't get me wrong,the Carpenters were a good group with some nice hits in say the 1970's but I mean, why do we need to subject Japanese teenagers songs that were popular when their parents were in elementary school?

When I have asked Japanese teachers about this, they give the answer that the melodies are nice, the lyrics are easy to understand. Yeah, 1970's easy listening. I mean every time I have to hear Mr. Postman (which I heard about 16 times today) or Top of the World, it takes me back to when to 1977 when I was 4 listening to this stuff on 8track 8 TRACK!!!!!!!!!!!!!!!!!!!!! 　When the Carpenters were a hot act,  I lived in Nova Scotia with a 40inch floor TV which was so big, it doubled as a display table, my parents drove the original Volkswagen Bettles (they had a blue and yellow one)
The TV had 2 channels, the internet was a military secret, cellphones were the same size as military radio sets, computers were large, and the Soviet Union was still a superpower.